Task.Start/Wait vs. Async/Await: What's the Difference in Handling Long-Running Operations?

Task.Start/Wait vs. Async/Await: Differences in handling time-consuming operations

In the world of multi-threading and asynchronous programming, it is crucial to understand the difference between Task.Start/Wait and async/await methods. These two technologies provide different mechanisms for handling time-consuming operations, thereby improving application responsiveness and performance.

Task.Start/Wait: synchronous blocking

In the Task.Start/Wait method, use Task.Factory.StartNew(Action) to create a new task and assign it a delegate to perform the time-consuming operation. The t.Wait() call then forces the calling thread to wait until the task completes execution.

Consider the following code snippet:

public void MyMethod()
{
  Task t = Task.Factory.StartNew(DoSomethingThatTakesTime);
  t.Wait();
  UpdateLabelToSayItsComplete();
}

In this example, the calling thread will execute the UpdateLabelToSayItsComplete() method only after the DoSomethingThatTakesTime() operation is completed. This method blocks processing on the calling thread, thereby delaying the execution of other tasks.

Async/Await: asynchronous non-blocking

In contrast, async/await methods use asynchronous programming to perform time-consuming operations without blocking the calling thread. The async void keyword allows a method to be asynchronous, where the await operator hands control to the caller until the task is completed.

Here is an updated code snippet using async/await:

public async void MyMethod()
{
  var result = Task.Factory.StartNew(DoSomethingThatTakesTime);
  await result;
  UpdateLabelToSayItsComplete();
}

In this case, the await result statement suspends the execution of the MyMethod() method until the DoSomethingThatTakesTime() task is completed. At the same time, the calling thread is free to perform other tasks.

Differences in understanding by analogy

Imagine a restaurant scenario: you order from the waiter and then choose to ignore your friend until the soup arrives (Task.Wait), or talk to your friend and have the waiter deliver the soup while the chat is paused (async/await).

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